Selective Electrochemical Reduction of Carbon Dioxide to Ethylene and Ethanol on Copper(I) Oxide Catalysts

作者：Dan Ren, Yilin Deng, Albertus D. Handoko, Chung Shou Chen, Souradip Malkhandi, Boon Siang Yeo · 发表于：ACS Catalysis · 年份：2015 · DOI：10.1021/cs502128q · 被引用次数：930 · 研究领域：CO2 Reduction Techniques and Catalysts、Ionic liquids properties and applications、Advanced battery technologies research

The selective electroreduction of carbon dioxide to C 2 compounds (ethylene and ethanol) on copper(I) oxide films has been investigated at various electrochemical potentials. Aqueous 0.1 M KHCO 3 was used as electrolyte. A remarkable finding is that the faradic yields of ethylene and ethanol can be systematically tuned by changing the thickness of the deposited overlayers. Films 1.7–3.6 μm thick exhibited the best selectivity for these C 2 compounds at −0.99 V vs RHE, with faradic efficiencies (FE) of 34–39% for ethylene and 9–16% for ethanol. Less than 1% methane was formed. A high C 2 H 4 /CH 4 products’ ratio of up to ∼100 could be achieved. Scanning electron microscopy, X-ray diffraction, and in situ Raman spectroscopy revealed that the Cu 2 O films reduced rapidly and remained as metallic Cu 0 particles during the CO 2 reduction. The selectivity trends exhibited by the catalysts during CO 2 reduction in phosphate buffer, and KHCO 3 electrolytes suggest that an increase in local pH at the surface of the electrode is not the only factor in enhancing the formation of C 2 products. An optimized surface population of edges and steps on the catalyst is also necessary to facilitate the dissociation of CO 2 and the dimerization of the pertinent CH x O intermediates to ethylene and ethanol.